Biopsy devices utilizing needle aspiration to extract tissue samples are well known to those skilled in the art. Such devices are extremely useful to obtain samples of tissue suspected of being cancerous so that such tissue may be examined in order to confirm such suspected diagnosis. Such devices are frequently used when sampling suspected cancerous tissue in the lungs, breasts, and prostate, as well as other body organs. Numerous other applications have also been found for these devices.
Generally, such biopsy instruments extract a sample of tissue from a tissue mass by either drawing a tissue sample into a hollow needle via an external vacuum force or by severing and containing a tissue sample within a notch formed on a stylet. Typical of such devices utilizing a vacuum force are U.S. Pat. No. 5,246,011 issued to Cailouette and U.S. Pat. No. 5,183,052 issued to Terwilliger. Such devices contemplate the use of advancing a hollow needle into a tissue mass and applying a vacuum force to draw a sample into the needle and hold the same therein while the tissue is extracted. Such devices, however, fail to adequately sever and contain such tissue samples as the vacuum force may not be sufficiently strong enough to sever and hold the sample within the biopsy needle.
Alternatively, other prior art biopsy instruments alternatively utilize a biopsy needle with a tissue sample recovery notch formed thereon to extract a specimen, such as described in U.S. Pat. No. 3,477,423 issued to Griffith, often referred to as the TRU-CUT needle and U.S. Pat. No. 4,776,346 issued to Beraha et al. Such devices, however, have the drawback of not effectively drawing a tissue sample of sufficient size into the biopsy notch on the cannula. Accordingly, such samples extracted by such biopsy needles may not provide sufficient tissue to perform an examination and thus require additional biopsies to be taken. Additionally, such needles have the disadvantage of having to be advanced into the desired tissue site such that the needle may possibly extend beyond the tissue site, thus resulting in the recovery of an inaccurate or non-usable tissue sample or injury to adjacent organs or structures by over-penetration.
Further attempts in the art have tried using specially designed cannulas to enhance the cutting and recovery of tissue samples as well as combining the application of a vacuum force to draw in a tissue sample into a biopsy cavity and then cutting the tissue contained therein. U.S. Pat. No. 4,708,147 issued to Haaga discloses a cannula for a biopsy needle designed to cut a sample of tissue and then applying a vacuum to the cannula such that the tissue is drawn into the cannula and thus retained therein for recovery. Additionally, U.S. Pat. No. 3,844,272 issued to Banko discloses a biopsy device wherein a suction force, created by a vacuum, draws a sample of tissue into a receiving compartment whereby two coaxial members are rotated relative to each other so that the members essentially coact to cut off the specimen and place it into a compartment. Such combination devices, however, fail to either sufficiently isolate a sample or fail to draw in a sample of sufficient size into a biopsy compartment. Additionally, such instruments typically are difficult to maneuver and manipulate and are not necessarily accurate or effective enough to achieve their desired purpose.
Accordingly, there exists a substantial need in the art to provide a tissue sample extractor capable of effectively and efficiently drawing in a suitable sample of tissue and isolating the tissue sample within the biopsy instrument. Additionally, there is a need for a biopsy device that is easy to use and can effectively be manipulated by one hand in light of the fact that it is advantageous to perform such biopsy procedures wherein the physician user is allowed to have an additional free hand. Furthermore, there is need in the art to provide a tissue sample extractor that not-only provides tissue samples of sufficient size, but allows the user to take multiple tissue samples without having to repeatedly puncture and penetrate the tissue mass. Further, it would be of even greater advantage to provide a tissue sample extractor having the above-mentioned features and also utilizing a disposable cannula assembly.